Discharge unloader



Aug. 2,1927'. 1,637,875 l f B. REDFIELD DISCHARGE UNLOADER y 'Filed Maron 4, 1927 y b l INVENTOR ms/A ORNEK infr drawings, in which Patented Aug. 2, 1927. v

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SNOWDEN B. REDFIELD, OF EASTON, PENNSYLVANIA, ASSGNOR TO INGER-SOLL-RAND COMPANY, OF JERSEY CTY, NET' t A CQEPORATGN OF NEW JERSEY.

DISCHARGE UNLOADER.

This invention relates to unloading` devices, but morer particularly tov discharge unloader for compressors and the like.

One object of the invention is to vent the cylinder of a compressorto atmospherer during` the unloaded period of the compres sor.

@ther objects will be in part obvious and in part pointed out hereinafter.

The invention consists ofthe combination of' elements and arrangement of parts substantially as hereinafter described and claimed and illustrated in the accompany- Figure l is a sectional elevation of 'a poition of a compressorcyliiider having` the invention applied thereto, and

Figure 2 isa sectional elevation of. the manipulating valve taken through Figure l on the line-2-2 looking iii tlie.diiection of the arrows. A j

Refeiing to the drawings, A designates the cylinder of a compressor supporting at one end a head B. The cylinder A may be the final stage cylinder of a .multi-stage compressor and is preferablyprovided with a bushing C to receive slidably the pistonv D The head B may be secured to the cylinder A in any suitable manner and in this instance the head B is provided with a bore E in alignment with the bushingP C to receive slida'bly theend of the piston D.

Seated on the'head B 'is an intake unloader designated generally by F. The'intake unloader is like that described in detail in the copendingg` application of S. B. Redfield, Serial No. 145,243, filed October 30, 1926, entitled Centralized interlockingY control for multi-stage compressors. The intake unloader accordinglyV has a plunger G actuated by a pist-on H for controlling` the admission of pressure fluid conveyed from' a lowerstage cylinder through a connection J to the cylinder A.

The pressure fluid conveyed by the connectionJ passes through a. passage K in the intake' unloaderF from whence it` flows through a` passage L in the intake unloader to a, chamber O formed in the head B.. A passage P leading from the cylinder bore E communicates with the 'chamber O through aport Q having at one end a seat R forV an inlet valve S which controls communication between the chamberA O' and the'passage E..

y applicati@ sied March 4, 1927. serial No. Narie.

, A passage T also leading from the cylinder bore vE chamber U'in the head B through a port 7 and communication between thel passage T and the discharge chamber U iscontrolled by a `discharge valve N of a well known type. f V

' tively actuating the plunger Gin the proper direction for preventing the admission of pressure fluidl from the connection J to the passage L whenever it is desired to unload.

the'cylinder A. Thesevmeans in the present instance consists of a pipe X leading from a' suitable source of pressure fluid supply (not shown) to the intake unloader F for conveying pressure iiuid thereto.

A valve chest Y is in this instance interposed in the pipey X to house a throttle valve Z having a passage to establish communication, between the opposed members of the pipe X connected to the valve chest. throttle valve Z also has a recess c' in one side to establish communication `between the portion of the pipe X which leads from the intake unloader v4to the valve'ehest and the atmosphere through ports d and e, said ports being' located in the valve chest on opposite sides of the pipe X.

communicates with a discharge' Convenient means are provided for selee- The i During` the normal operation or the device so far described, that is, during the loaded period of the compressor, pressure fluid conveyed from ay lower stagecylinder through the connection J enters the passage l and from thence flows through the passage L into the chamber O, it being, of course, understood that the plunger Gr is free to move from the closed position indicated inthe drawing'. As the piston D is retracted in the cylinder A, the inlet valve S will be raised to admit pressure fluid from the chamber 0 into the cylinder A through the port Q and the passage P. The pressure fluid is then discharged into tie discharge chamber `U through the port V and the passage T.

During` the operation so far described, the throttle valve'Z'will occupy al position which will cut off the flow ofthe pressure fluid froml the pipe X intothe intake unloader and will openJ the intake unloader to the at-v mosphere through the pipe X,-the recess 0 in the valve and one or both of the portsv d and e. It, then it bedesired tof unload the cylinder A, the throttle valve Z may be rotated to the position illustrated in thel drawings. In this position of the throttle valve, pressure fluid will flow into the'intake unioader F and acting upon the piston II will actuate said piston in the required direction to close the plunger G and thus cut oil communication between the connection J and the cylinder A.

After the supply of pressure' fluid to the cylinder A has been cut off by the plunger G, the piston D will,' in the absence of leakage of pressure fluid into the cylinder, draw a vacuum. The difficulty of machining the cooperative surfaces of the various elements which control the admission, fof pressure fluid to the cylinder to fits which will absolutely prevent leakage of pressure fluid. are, however, well Vrecognized and in practice some pressure fluid at times leaks into the cylinder A during the. unloaded period and is compressed thereinto a higher stage and discharged into the final receiver. In order to prevent an occurrence of this kind in the present instance, a discharge unloader designated generally by f is disposed on the head B and has a passage f/ which communicates with the discharge Y chamber` Il through a port iin the head B.

it :its ot-her end the. passage g comnuinicates with a valveV chamber' l: formed transversely through the casing o; of the discharge un-1 loader. In the present instance a passage p leading Vfrom the valve chamber le affords communication between said valve chamber' and a discharge pipe. q which may lead to a final receiver (not shown).

"In order to prevent the pressure 'fluid discharged into the pipe g from` again returning into the discharge chamber Il, a check valve r of a well known type is disposed in one `end of the valve Vchamber 7c and is normally held closed by a spring s, said spring being seated in the check valve r and bears with its outer end againsta plug t which seals the end of the valve chamber and also serves to secure in position a bushing a in which the check valve i reciprocates.

In the opposite end of the valve chamber 7c is disposed a valve cage 'u in which isdis posed a valve fw to control a port :a in the inner end of the valve cage o. The port ai affords communication between the passage ,g and a here g/ in the valve cage in which the valve w reciprocates. A vent e is in this instance formed in one side of the valve cage o and the casing o` to afford communication between thebore y and the atmosphere. l

The outer end of the valve zu may be enlarged as at 2 to form an abutment for a piston?) slidable in the valve cage o. `Bolts 5 screwed into the end of the casing `0 in this instance hold the valve cage firmly in operative position. Preferably, a flange 6 is formed on the valve'ecage to act as an ablutment for a. collar through which the bolts 5 extend.

Suitable means are provided -toginsure closing of the valve w during the time that the cylinder A :is unloaded, and to that end .aspring is interposed between the valve fw and the piston 3. In the present instance the spring" is seatedin a recess 16 formed in the piston 3. The recess is of sufficient depth to enable the spring to be 'pressed thcreinto when-ever the piston 3 and the valve w are in Contact with each other.

A closure 4for the end of the valve chamber 7c is inthis instance provided in the form of a plug 8 having a passa-ge 9 which rsimultaneously cut ofi".

In the operation of the devilcpeL when ever the cylinder A is unloaded andtherevfore drawing a. vacuum, any pressure fluid leaking into the cylinder bore E will be discharged into the discharge chamber U from whence it will pass through the` pas! sages h and a? to act against the valve fw; IVhile the compressor is operating under these conditions.` the flou7 of pressure fluid to t-he chamber if: will, of course, also have been cut off. However, the spring 15 will then hold the piston 3 rearwardly against the plug 8 and will also tend to hold the valve w closed. After the pressure fluid discharged in the discharge chamber U and the various passages leading` to` the bore y ofthe valve cage reaches a value which will. enable it to overcome the force of the spring 15, thev valve fw `will be unseated and such pressure fluid will then bel exhausted through the bore y and through the vent e to the atmosphere.` The spring 15 by its compressive action will then promptly close the valve fw and prevent atmospheric air from being drawn into the `discharge chamber on the reverse `stroke of the piston. i

I claim: i l 1.` A discharge unloader` fora compressor cylinder, comprisinga casingr adapted to be connected in the dischargeline of the compressor, said casing having a passage for conveying pressure fluid from the cylinder to the dischargeline, said casinghaving a vent affording communication between the passage and the atmosphere, and means in `the :casing controlling the ventf'said 'Ill ' affording communication between the pasl sage and the atmosphere, and spring pressed means for controlling communication between the passage and the vent during theunloaded period of the cylinder.

3. A discharge nnloader'for a compressor cylinder, comprising a casing adapted to be connected in the discharge line of the compressor, said casing having a passage forming a vpart of the discharge line, a vent in the casing leading from the passage to the atmosphere, a valve controlling communication between the passage and the vent, said valve being held closed by pressure fluid during the loaded period of the cylinder, and a spring tending to hold the valve in closed position during the unloaded period of the cylinder.

4. A discharge unloader for a compressor cylinder, comprising a casing adapted to be connected in the discharge line of the compressor.y said` casing having a` passage for conveying pressure flnid from the cylinder to the discharge line, a. valve chamber inr the casing communicating with the passage, a vent in the casing affording coinmuication between the valve chamber and the ath mosphere, a valve in the valve chamber controlling communication between the passage and the vent, means conveying pressure fluid to the valve chamber for holding the valve closed during the loaded period of the cylindei, and a spring acting against the valve to close the valve in the absence of pressure fluid in the valve chamber during the unloaded period of the cylinder.

hold the valve closed pressor, said casing having a valve chamber,

a passage in the casing for conveying pressure fluid from the cylinder to the discharge line, said passage also communicating with the valve chamber, a vent inthe casing affording communication between kthe valve chamber and the atmosphere, a valve reciprocable in one end of the valve chamber contro`ling the vent, a piston in the other end of the valve chamber adapted to be pressed against the valve by pressure fluid for holding the valve closed during the loaded period of the cylinder, and a spring between the valve and the-piston tending to during the unloaded period of the cylinder. l

6. A discharge uiiloader for a compressor cylinder, comprising a casing adapted to be connected in the discharge line of the compressor, said casing having a valve chamber, a passage in the casing forming a part of the discharge line, said passage also communicating with the valve chamber, a vent in the casing leading from the valve chamber to the atmosphere, a valve in the inner end of the valve chamber controlling coinmunication between the passage and the vent, a piston in the outer end of the valve chamber, said piston being of larger diameter than the valve, means conveying pressure fluid to the valve chamberto act against theY piston` for holding the valve closed during the loaded period ofthe cylinder, a spring between the valve and the piston to effect closing of the valve during the unloaded period of the cylinder, and means for selectively controlling the admission and exhaust of-pressure fluid to and from the valve chamber.

In testimony whereof I have signed this specification. K

SNOWDEN B. REDFIELD. 

